Energy consumption worldwide is generally increasing, and conventional hydrocarbon resources are being consumed. In an attempt to meet demand, the exploitation of unconventional resources may be desired. For example, highly viscous hydrocarbon resources, such as heavy oils, may be trapped in tar sands where their viscous nature does not permit conventional oil well production. Estimates are that trillions of barrels of oil reserves may be found in such tar sand formations.
In some instances these tar sand deposits are currently extracted via open-pit mining. Another approach for in situ extraction for deeper deposits is known as Steam-Assisted Gravity Drainage (SAGD). The heavy oil is immobile at reservoir temperatures and therefore the oil is typically heated to reduce its viscosity and mobilize the oil flow. In SAGD, pairs of injector and producer wells are formed to be laterally extending in the ground. Each pair of injector/producer wells includes a lower producer well and an upper injector well. The injector/production wells are typically located in the pay zone of the subterranean formation between an underburden layer and an overburden layer.
The upper injector well is used to typically inject steam, and the lower producer well collects the heated crude oil or bitumen that flows out of the formation, along with any water from the condensation of injected steam. The injected steam forms a steam chamber that expands vertically and horizontally in the formation. The heat from the steam reduces the viscosity of the heavy crude oil or bitumen which allows it to flow down into the lower producer well where it is collected and recovered. The steam and gases rise due to their lower density so that steam is not produced at the lower producer well and steam trap control is used to the same affect. Gases, such as methane, carbon dioxide, and hydrogen sulfide, for example, may tend to rise in the steam chamber and fill the void space left by the oil defining an insulating layer above the steam. Oil and water flow is by gravity driven drainage, into the lower producer well.
With heavy oil recovery methods such as SAGD that utilize steam to heat the reservoir and lower oil viscosity, when the produced fluid comes back to the surface it includes water in oil emulsions that may be difficult and expensive to separate. Also, for the water recovered from the produced fluids to be reused in the steam generation facility, it should include relatively few contaminants (e.g., oil).
Generally speaking, typical methods to separate oil from water rely on a combination of high temperatures, chemical treatment, gravity separation, and/or filtration. However, such configurations may not provide desired performance in some applications, may be limited in their ability to scale for field applications, and considerably increase treatment costs for example.
Another approach for treating hydrocarbons is set forth in U.S. Pat. Pub. No. 2014/0014494 to Blue et al., which is assigned to the present Applicant and is hereby incorporated herein in its entirety by reference. This approach is directed to a radio frequency (RF) hydrocarbon resource upgrading apparatus that includes a first hydrocarbon resource upgrading path that includes a plurality of first RF power applicator stages coupled in series. Each first RF power stage is configured to apply RF power to upgrade a hydrocarbon resource passing therethrough. The apparatus also includes a second hydrocarbon resource upgrading path that includes at least one second RF power applicator stage coupled in parallel with at least one of the first RF power applicator stages. The second RF power applicator stage is configured to apply RF power to upgrade a hydrocarbon resource passing therethrough. Accordingly, the RF hydrocarbon resource upgrading apparatus upgrades the hydrocarbon resource passing through multiple hydrocarbon resource upgrading paths. This may be particularly advantageous for efficiently upgrading the hydrocarbon resource according to different operating parameters to output one or more upgraded hydrocarbon resource products with different desired characteristics, for example.
Despite the existence of such configurations, further enhancements for emulsion treatment and water/hydrocarbon fluid separation may be desirable in some instances.